> I have always wondered why in carbonated drinks, beer, etc, bubble originate at a certain spot over and over for no apparent reason....................
Surface impurities in the container.
Bubbles form when the dissolved gas, carbon dioxide in this example, is super saturated. The gas comes out of solution, forming bubbles, more easily at surface defects and asperities. The bubbles form less easily on smooth surfaces, and even less easily in the bulk liquid, away from any surface. The surface defects typically are always in the same place, so bubbles will preferentially form there, which is what you see.
AKA, a dirty glass.......................🤦♀️